An L-dopa-like depressor action of L-threo-dihydroxyphenyl-serine in the rat caudal ventrolateral medulla
- 作者：Furukawa ; Nobuya ; Goshima ; Yoshio ; Miyamae ; Takeaki ; Nishihama ; Masamitsu ; Okumura ; Fukuichiro ; et. al.
- 关键词：L-DOPA ; L-threo-dihydroxyphenylserine ; neurotransmitter ; caudal ventrolateral medulla ; rostral ventrolateral medulla ; central cardiovascular control ; L-DOPA methyl ester
- 刊名：Life Sciences
- 出版年：1997
- 期刊代码：62_00243205
- 类别：imm
- 出版时间：August 15, 1997
- 卷：61
- 期：12
- 页码：1177-1183
- 文件大小：365 K
摘要
We have proposed that L-3,4-dihydroxyphenylalanine (L-DOPA) is a neurotransmitter and/or neuromodulator in the central nervous system (1). In this study, we investigated whether or not L-threo-dihydroxyphenylserine (L-threo-DOPS), a synthetic amino acid structurally related to L-DOPA, microinjected into the caudal ventrolateral medulla (CVLM) and the rostral ventrolateral medulla (RVLM) shows cardiovascular actions similar to those of L-DOPA in anesthetized rats. When L-threo-DOPS was microinjected into CVLM, it produced dose-dependent (0.01-3 ng) depressor and bradycardic responses. D-threo-DOPS (3 ng) produced no effect. The responses to L-threo-DOPS (1 ng) were almost completely blocked by L-DOPA methyl ester (1 μg), a competitive antagonist for L-DOPA, supporting the existence of an L-threo-DOPS-sensitive recognition site for L-DOPA in CVLM. Microinjection of L-threo-DOPS into RVLM, however, showed no effect (0.001-100 ng), which contrasted with the cardiopressor action of L-DOPA applied in RVLM. In RVLM, there may exist an L-threo-DOPS-insensitive recognition site for L-DOPA.